Incorrect error response after user sends invalid data

When the user sends invalid data to controller configuration via Netconf MDSAL Northbound, the returned error response is (the "message-id" attribute can vary and the number at the end of the <error-message> element can vary as well):

<?xml version="1.0" encoding="UTF-8" standalone="no"?> <rpc-reply message-id="71" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <rpc-error> <error-type>application</error-type> <error-tag>operation-failed</error-tag> <error-severity>error</error-severity> <error-message>Transaction commit failed on canCommit encountered an unexpected failure 3</error-message> </rpc-error> </rpc-reply>

It is not clear from the error message that the problem here is invalid data. Actually, the error message suggests that the ODL suffered some scary internal error.